Automated washing machines (such as laundry washing machines) often include mechanisms for dispensing additives into a washing chamber (e.g., a drum of a laundry washing machine). Some dispensers contain receptacles for different additives, which can include detergents, whiteners, fabric softeners, scents, rinse aids, etc. Typically, a user fills a dispenser chamber with one or more additives. During a wash cycle, water is then automatically introduced into the dispenser chamber and mixes with the additive. The water/additive mixture then flows into a separate washing chamber.
One type of additive dispenser is described in commonly-owned U.S. Patent Application Publication No. 2004/0011089 (titled “Washing Aid Dispenser and Washing Machine Comprising Said Dispenser”). The dispenser described in said application includes an arrangement of siphon posts positioned within a dispenser compartment. Cap pieces extend over the tops of the siphon posts. When water is introduced into the dispenser cavity and rises above the height of one or more of the siphon posts, a mixture of water and an additive is drawn from the dispenser cavity through the siphon post(s) and flows into the wash drum.
The dispenser described in U.S. Pub. No. 2004/0011089 includes multiple siphon posts of different diameters and heights in order to provide increased suction for removal of denser additives. Under some conditions, however, that dispenser (as well as other siphoning dispensers) may fail to completely evacuate a water/additive mixture from a dispenser by the end of a wash cycle. For example, some highly viscous additives can interfere with a siphoning action and interrupt flow from a dispenser cavity. When additive mixture remains after a wash cycle, the user may find it necessary to remove the entire dispenser unit to dump out the remaining mixture. In some cases, the additive mixture remains in the dispenser until the water component evaporates, thereby leaving a hardened residue.